Yuzhi Xiang

The effect of a hydrogen bond on the supramolecular self-aggregation mode and the extent of metal-free benzoxazole-substituted phthalocyanines

Two novel metal-free phthalocyanines have been designed and synthesized, namely tetra{[1H-benzo(d)imidazol-2-yl]thiol}phthalocyanine (TBIT-Pc) and tetra{[benzo(d)thiazol-2-yl]thiol}phthalocyanine (TBTT-Pc). These two compounds showed similar structures, while imidazolyl-NH in the substitutes of TBIT-Pc could form more hydrogen bonds. TBIT-Pc and TBTT-Pc were fully characterized by elemental analysis, 1H NMR, MALDI-TOF MS, FT-IR and the UV-Vis absorption spectrum. The self-assembly properties of TBIT-Pc and TBTT-Pc were comparatively studied. TBIT-Pc and TBTT-Pc were present as monomers in DMF in the concentration range of 9.04–20.3 μM. Depending mainly on the intermolecular hydrogen bonding (N–H⋯N) between benzimidazole substitutes, “head-to-tail” J-aggregates of TBIT-Pc were formed in DMSO, while there was no aggregation of TBTT-Pc in the same solvent. “Face-to-face” H-aggregates of TBIT-Pc and TBTT-Pc were formed with the addition of water to the solutions of DMSO, and the degree of aggregation increased with the introduction of H-bonds (N–H⋯N) in the benzimidazole substitutes of TBIT-Pc. The atomic force microscope (AFM) image and dynamic light scattering (DLS) displayed the formation of well-defined nanoparticles with a diameter of ca. 30 ± 15 nm with J-type aggregation of TBIT-Pc. And the dendritic nanostructures with H-aggregates of TBIT-Pc and TBTT-Pc with different size were observed from transmission electron microscopy (TEM) images. The possible mechanism of the effect of H-bonds on the formation of J-aggregates of TBIT-Pc and the H-aggregation of TBIT-Pc and TBTT-Pc was also discussed. In the formation process of aggregates, H-bonds and π–π interaction may be the dominant factors. In addition, the nanostructures fabricated from TBIT-Pc and TBTT-Pc showed good semiconducting properties revealed by current–voltage measurements.

The Effect of Metal Introduced Over ZSM-5 Zeolite for C9 Heavy Aromatics Hydrodealkylation

Abstract Five different (Bi, Ni, Mo, Pt, H)/ZSM-5 catalysts were tested for hydrodealkylation (HDA), isomerisation, dehydrogenated, cyclistion, and poly-alkyl-aromatics activities. Experiments were performed in a fixed-bed microreactor between 300°C and 420°C, at a total pressure of 0.8 MPa and a liquid hourly space velocity of 1.0 h−1. Pt (Mo)/ZSM-5 catalysts enhanced activity in terms of better balance between metal nanoparticles formed and acid sites. Pt-loading catalysts were the best overall catalysts, producing high C9 alkyl-aromatics (isopropylbenzene) conversion (95.9%), high HDA selectivity (92.2%), and relatively low reaction temperature. Mo-loading catalysts, despite producing the high conversion, required the higher reaction temperatures.

Synthesis, characterization and catalytic oxidation performance of new planar binuclear phthalocyanines sharing the benzene ring

The crude product of hexacarboxy biphtalocyanines cobalt (CoBPcC6) was synthesized by fusing trimellitic anhydride, pyromellitic dianhydride, urea and CoCl2 · 6H2O with ammonium molybdate as catalyst and then hydrolyzed under alkaline conditions. The crude product was isolated by acidifying with hydrochloric acid followed by filtration, then purified by reprecipitation from concentrated sulfuric acid followed by chromatography on silica gel column. CoBPcC6 was characterized by IR, UV-vis, 1H NMR, elemental analysis, etc. The activity of CoBPcC6 catalyst for extractive sweetening was evaluated by studying mercaptide oxidation. It was found that the performance of this immobilized catalyst was better than the commercial immobilized catalyst.

Solid-phase synthesis and catalytic sweetening performance of sulfonated cobalt phthalocyanine from sulfonated phthalic anhydride mixture

A relatively green, efficient and economical synthetic route for the one-step solid-phase synthesis of sulfonated cobalt phthalocyanine from sulfonated phthalic anhydride mixture was studied, and could solve the serious problems of waste acid pollution and the low utilization of materials in the direct sulfonation of phthalocyanine. The optimal reaction conditions were using a phthalic anhydride mixture with a sulfonation degree of 60% as the raw material, a ratio of urea to PA–SPA mixture of 4 : 1, a ratio of cobalt chloride to PA–SPA mixture of 1 : 4, ammonium molybdate (1 wt%) as catalyst, and carrying out the reaction at 260 °C for 3 hours. Under these optimal conditions, a yield of 52.9% can be achieved. Through sweetening experimental studies, the synthesized sulfonated cobalt(II) phthalocyanine had better sweetening performance than the industrial catalysts, in both the liquid–liquid sweetening and fixed bed sweetening experiments. A sweetening rate of 93% can be achieved in 20 min with the synthesized catalyst in a fixed bed.

Effect of H2S on the transformation of 1-hexene over NiMoS/γ-Al2O3 with hydrogen

Abstract The effect of H2S contents on the transformation of 1-hexene with hydrogen over NiMoS/γ-Al2O3 catalyst was investigated. Inhibition of H2S on both hydrogenation and isomerization reactions of olefin has been demonstrated. And the promotion effect of H2S on the formation of C6 thiols and C12 thioethers has also been observed. It was found out that there was only one type of active site on the NiMoS/γ-Al2O3 for reactions which include hydrogenation reaction, isomerization reaction and sulfides formation reaction, and the formation reactions of sulfides were superior to both hydrogenation and isomerization reactions. The reaction network for the conversion of 1-hexene in the presence of H2S was proposed.

Structure and adsorptive desulfurization performance of the composite material MOF-5@AC

A composite material (MOF-5@AC) of MOF-5 and AC was successfully prepared. After characterization by a variety of means, it was shown that MOF-5 was covered on the surface of AC and existed in the form of microcrystals. A new micro-mesoporous pore appeared at 1.8–5 nm, while MOF-5 and AC are both microporous materials. And the thermal and water stability of MOF-5@AC is better than that of MOF-5. The adsorptive desulfurization experiment showed that the performance of the composite material was higher than that of the two parent materials, especially for the large molecular thiophenic sulfur compounds. And the reuse performance of MOF-5@AC after regeneration was also significantly improved compared the parent materials. The ratio of raw materials of composite materials plays an important role in the microstructure, morphology and desulfurization properties. After screening the ratio of raw materials, MOF-5@AC with a ratio of 1 : 5 showed the best desulfurization performance. The theoretical calculation results are in accordance with the desulfurization performance of the composite material (MOF-5@AC), which shows that MOF-5 is well dispersed on the AC surface and the pores are well exposed.

Molecular recognition with cyclodextrin polymer: a novel method for removing sulfides efficiently

A series of cyclodextrin polymers (CDPs) were synthesized and they were used for removing different sulfides by molecular recognition. Different CDPs showed a higher desulfurization efficiency for sulfides with an aromatic ring structure than those with an aliphatic chain structure. For different cyclodextrin polymers, β-CDP has a more suitable cavity size for removing DBT. Moreover, it has a good synergetic effect of adjacent cyclodextrin cavities and good electronic interactions with DBT. For these reasons, β-CDP showed the best desulfurization performance, in particular it has good performance for deep desulfurization by forming inclusion complexes and excellent selectivity for removing DBT. Meanwhile, the β-CDP showed good regeneration performance. Various characterization measurements were used to characterize the β-CDP before and after desulfurization of DBT, the results of which showed that it had advantages of wide application temperature range and good structure stability before and after desulfurization. Finally, a molecular recognition mechanism for removing sulfides efficiently was proposed.

Selective functionalization of external and internal surface of MCM-41 for adsorptive desulfurization

MCM-41 was selectively functionalized with CuO on the external surface and Cu2+ coordinated by organosilanes on the internal surface. The production of CuO and removal of template were achieved in one step, which is convenient and a save of energy. Results of transmission electron microscopy indicate the presence of CuO on outer surface of MCM-41. The successful grafting of organosilanes was confirmed by 13C and 29Si nuclear magnetic resonance. The prepared M(CuO)N(Cu) shows more comprehensive desulfurization performance due to the simultaneous and independent incorporation of CuO and copper ions. Dimethyl sulfide and dimethyl disulfide are selectively adsorbed on external surface of M(CuO)N(Cu), while tert-butyl mercaptan can be adsorbed on both external and internal surface of M(CuO)N(Cu).

Self-assembled core–shell nanospheres and dendritic nanostructure of novel tetra-(3-phenyprop-2-allyloxy) phthalocyanine in different solvents

Novel metal-free tetra-(3-phenyprop-2-allyloxy) phthalocyanine (TPAO-Pc) was synthesized and characterized by nuclear magnetic resonance spectrum (1H NMR), MALDI-TOF MS, Fourier-transform infrared (FT-IR) and UV-Visible absorption (UV-Vis) spectra. The effects of concentrations and solvents on the properties of self-assembly were investigated via absorption and fluorescence spectra, transmission electron microscopy (TEM). TPAO-Pc was stable in most organic solvents, such as toluene, acetone and dimethylsulfoxide (DMSO). However, the TPAO-Pc exhibited the tendency of forming “face-to-face” stacking mode self-assemblies (H-aggregate) in DMSO–water and acetone–water mixed solutions. Self-assembly of the TPAO-Pc was also demonstrated by fluorescence spectra. The TEM images displayed the core–shell nanospheres and dendritic nanostructure of TPAO-Pc formed in the DMSO–water and acetone–water mixed solutions, respectively. The mechanism of the self-assemblies growth was proposed on the basis of the experimental results. The morphology of the TPAO-Pc self-assemblies was related with the selected solvent conditions and the aggregation time. H-bond, π–π interaction may be the main driving force for the formation of core–shell nanospheres and dendritic nanostructure.

Effect of Hydrogen Sulfide Content on the Recombination Reaction Between 1-hexene and Hydrogen Sulfide with Hydrogen

Abstract The recombination reaction between H2S and 1-hexene with H2 was detected. The catalyst used was NiMoS/γ-Al2O3; the volume proportion of 1-hexene was 10 (vol%); H2S content was 500, 1,000, 2,000, 3,000, 4,000 μg/g, respectively; initial H2 pressure was 2.0 MPa; and reaction time and temperature were 2.0 hr and 473 K, respectively. It was revealed that, in the reaction system, as the content of H2S increased, the content of hexanethiol and total sulfide in the reaction system increased significantly. The inhibition of hydrogenation by H2S and the isomerization of 1-hexene toward 2-hexene and 3-hexene were researched. As the content of H2S increased, the mass fraction of hexane, 2-hexene, and 3-hexene decreased and the remaining 1-hexene increased in the reaction system; therefore, H2S inhibits the formation of hexane, 2-hexene, and 3-hexene.